The decision ends months of speculation. The first phase of the network, between London and Birmingham, due to come into operation in 2026, will cut journey times by more than 30 minutes. The transport secretary, Justine Greening, announced a series of tweaks to the route from London to Birmingham, intended to appease campaigners from the Tory heartlands. About 22.5 miles of the amended route is underground, an increase of 50% on the original plan.